CN111483588A

CN111483588A - Differential braking of aircraft landing gear wheels

Info

Publication number: CN111483588A
Application number: CN202010181874.7A
Authority: CN
Inventors: 乔治·豪厄尔; 利维耶·本; 路易斯-埃马纽埃尔·罗马纳
Original assignee: Airbus Operations GmbH; Airbus Operations SAS
Current assignee: Airbus Operations GmbH; Airbus Operations SAS
Priority date: 2014-07-18
Filing date: 2015-07-17
Publication date: 2020-08-04
Anticipated expiration: 2035-07-17
Also published as: US20160016661A1; RU2015131643A; CN105270610A; CA2896901A1; GB2528317A; RU2015131643A3; GB201412769D0; US9809302B2; EP2974957B1; RU2703477C2; CN111483588B; EP2974957A1; CN105270610B

Abstract

The present invention provides a method of braking left and right landing gear wheels, respectively, of an aircraft on left and right sides, receiving a desired left braking parameter L for the left wheel, and receiving a desired right braking parameter R for the right wheel, braking the left wheel with a reduced left braking parameter L 'that is less than the desired left braking parameter L, and braking the right wheel with a reduced right braking parameter R' that is less than the desired right braking parameter R, maintaining a difference between the braking parameters such that L '-R' is L-R.

Description

Differential braking of aircraft landing gear wheels

The present application is a divisional application of the applicant's invention patent application entitled "differential braking of aircraft landing gear" filed on 17.7.2015 with application number 201510424306.4 by airbus operating limited.

Technical Field

The invention relates to a method for braking a left landing gear wheel and a right landing gear wheel and a related control system.

Background

Conventional large jet aircraft include a steerable nose landing gear (N L G) assembly and a plurality of main landing gear (M L G) assemblies, with the N L G assembly positioned toward the front of the fuselage and the M L G assemblies positioned toward the rear of the N L G assembly and distributed laterally about the plane of symmetry of the aircraft.

In some cases, the pilot of the aircraft may command differential braking of left M L G and right M L G — braking left M L G to a high degree causes a left turn and braking right M L G to a high degree causes a right turn.

US 464646242 discloses an autobrake function which applies a constant deceleration during the de-rotation phase of the aircraft, which is the phase after landing at M L G but before landing at N L G, before landing.

Disclosure of Invention

A first aspect of the invention provides a method of braking respective left and right landing wheels of an aircraft on left and right sides, the method comprising receiving a desired left braking parameter L for the left wheel, receiving a desired right braking parameter R for the right wheel, braking the left wheel with a reduced left braking parameter L 'that is less than the desired left braking parameter L, braking the right wheel with a reduced right braking parameter R' that is less than the desired right braking parameter R, and maintaining a difference between the braking parameters such that L '-R' is L-R.

The first aspect of the present invention also provides a braking control system programmed to control left and right brakes of an aircraft by receiving desired left braking parameters L for the left brakes, receiving desired right braking parameters R for the right brakes, determining reduced left braking parameters L ', wherein the reduced left braking parameters L' are less than the desired left braking parameters L, determining reduced right braking parameters R ', wherein the reduced right braking parameters R' are less than the desired right braking parameters R, wherein L '-R' ═ L-R, and outputting the reduced braking parameters to the left and right brakes.

The first aspect of the invention reduces the amount of braking applied to the wheels (compared to the desired braking parameters), thereby limiting the risk of damage to the aircraft, while maintaining the difference between the braking parameters such that: any desired differential braking is applied, although the braking is generally reduced.

In a preferred embodiment of the present invention described below with reference to table 1, the controller performs the first aspect of the present invention when the controller is in logic state B.

Reduced braking parameters may be applied regardless of total braking commanded by desired braking parameters L + R, but in a preferred embodiment, the method further includes determining whether a sum L + R of the desired left braking parameter and the desired right braking parameter exceeds a threshold, braking the left and right wheels with desired left braking parameter L and desired right braking parameter R, respectively, in response to a determination that the sum L + R does not exceed the threshold, and braking the left and right wheels with reduced left braking parameter L 'and reduced right braking parameter R', respectively, in response to a determination that the sum L + R exceeds the threshold.

The sum of reduced braking parameters L '+ R' may vary, but more preferably, the sum of reduced braking parameters L '+ R' is substantially equal to the threshold value.

A second aspect of the invention provides a method of braking first and second landing gear wheels, respectively, of an aircraft on first and second sides, the method comprising: receiving a first desired braking parameter for the first wheel; receiving a second desired braking parameter for the second wheel, wherein the second desired braking parameter is less than the first desired braking parameter; determining differential braking parameters from the difference between the braking parameters; judging whether the differential braking parameter exceeds a threshold braking parameter or not; braking the first wheel with the differential braking parameter in response to a determination that the differential braking parameter does not exceed the threshold braking parameter; and braking the first wheel with the threshold braking parameter in response to a determination that the differential braking parameter exceeds the threshold braking parameter.

Wherein the landing gear wheels are located on opposite sides of a plane of symmetry of the airframe of the aircraft.

Each desired braking parameter defines a hydraulic pressure, a braking torque, or an angular deceleration of the landing gear wheel.

The desired braking parameters are received from the pilot via one or more user input devices.

The second aspect of the invention also provides a brake control system programmed to control a first brake and a second brake of an aircraft by: receiving a first desired braking parameter for a first brake; receiving a second desired braking parameter for a second brake, wherein the second desired braking parameter is less than the first desired braking parameter; determining a differential braking parameter indicative of a difference between the desired braking parameters; judging whether the differential braking parameter exceeds a threshold braking parameter or not; outputting a differential braking parameter to the first brake in response to a determination that the differential braking parameter does not exceed the threshold braking parameter; and outputting the threshold braking parameter to the first brake in response to a determination that the differential braking parameter exceeds the threshold braking parameter.

The second aspect of the invention provides an alternative solution to the same problem as the first aspect of the invention-how to limit the risk of damage to the aircraft while maintaining the difference between the braking parameters such that any desired differential braking is still applied. If the differential braking parameter is less than the threshold value, the differential braking parameter is applied to the first wheel, but if the differential braking parameter is greater, the amount of braking applied to the first wheel is limited to the threshold value in order to avoid damage.

Typically, when the first wheel is braked with the differential braking parameters and the threshold braking parameters, the second wheel is not braked.

In a preferred embodiment of the invention described below with reference to table 1, the controller performs the second aspect of the invention when the controller is in logic states C to F.

The following discussion is directed to two aspects of the present invention.

The braking parameter may be the hydraulic pressure of the wheel (in the case of a hydraulic braking system), the braking torque, the angular deceleration, or any other suitable parameter indicative of the amount of braking applied.

The desired braking parameters may be received from a computerized automatic braking system, but more preferably, the desired braking parameters are received from the pilot via one or more user input devices, such as pedals.

The method may be performed during low speed glide when the aircraft is in a de-spinning phase with the landing gear wheels on the ground after landing and the nose gear of the aircraft not on the ground, or at any other time.

In a preferred embodiment, the method further comprises: judging whether the aircraft is in an unwinding stage; and performing the method in response to a determination that the aircraft is in the de-rotation phase.

The desired braking parameters may be received directly from both pedals (as independent inputs) or indirectly through a single lever, for example, where the lever inputs the sum L + R of the desired braking parameters by moving the lever back and forth and the difference L-R between the desired braking parameters by moving the lever left and right.

Typically, the landing gear wheels are located on opposite sides of a plane of symmetry of the airframe of the aircraft. Preferably, the wheels are spaced the same distance from the plane of symmetry.

Drawings

Embodiments of the invention will now be described with reference to the accompanying drawings, in which:

FIG. 1a is a front view of an aircraft;

FIG. 1b is a left side view of the aircraft;

FIG. 1c is a plan view of the aircraft;

FIG. 2 is a schematic diagram illustrating a control system for controlling the brakes;

FIG. 3 is a logic diagram illustrating how the control system determines that the aircraft is in the de-rotation phase; and

FIG. 4 is a logic diagram illustrating how the control system determines the output braking parameter.

Detailed Description

Fig. 1a to 1c show an aircraft 1, the aircraft 1 having an airframe which includes a fuselage 2 from which

wings

3, 4 extend outwardly. The body has a plane of symmetry 5 containing a longitudinal axis 6 (also called the roll axis). The aircraft 1 has a centre of gravity 7.

The aircraft has landing gear which supports the aircraft when the aircraft is on the ground and controls its movement during ground manoeuvres such as landing, taxiing and take-off the landing gear comprises a nose landing gear (N L G) assembly 10 and a pair of left and right chordal main landing gear (M L G) assemblies 11, 12, with the N L G assembly 10 located forward of the centre of gravity 7 and the

M L G assemblies

11, 12 located aft of the centre of gravity 7 and arranged on either side of the plane of symmetry 5 in other embodiments the aircraft may comprise further M L G assemblies, these M L G assemblies being arranged generally in pairs and on either side of the plane of symmetry 5.

The N L G assembly 10 has a pair of steerable wheels that can be rotated by a steering actuator to steer the aircraft.

The M L G assemblies 11, 12 each include a 4-wheeled truck (alternatively, a 6-wheeled truck or a truck having any number of wheels would be equally suitable) having brakes 13, 14 (as shown in FIG. 2) which 13, 14 are capable of acting on the wheels to decelerate the truck. each

brake

13, 14 applies a clamping force to a stack of

carbon brake disks

13a, 14a (stator and rotor) to transfer a braking torque to the wheels, causing a longitudinal deceleration force to be transferred to the truck.

The

brakes

13, 14 of the

M L G assemblies

11, 12 may be used to assist in steering the aircraft by differential braking, where differential braking is the intentional application of unbalanced braking forces to both sides of the aircraft plane of symmetry 5 to create a net yaw moment to steer the aircraft.

Braking and steering operations may also be assisted by other systems (e.g., spoilers) and other control surfaces and engines of the aircraft.

The

brakes

13, 14 are powered by hydraulic pressure, with higher hydraulic pressure providing higher braking torque. In particular, each brake has a

servo valve

13b, 14b, the

servo valves

13b, 14b being controlled by an electrical control signal on an

input line

13c, 14c, the value of the control signal determining the hydraulic pressure on a

hydraulic output line

13d, 14d, which in turn exerts a clamping force on the brake disc.

The aircraft 1 includes a cockpit brake control system 20 (shown in FIG. 2), the cockpit brake control system 20 receiving command inputs from a pair of left and right brake pedals 21, 22 operated by the pilot, during normal operation, when the left pedal 21 is depressed, an increasing hydraulic pressure is applied to the left brake disk 13a, and when the right pedal 22 is depressed, an increasing hydraulic pressure is applied to the right brake disk 14 a. the relationship between pedal position and hydraulic pressure is shown below in Table 2-when the pedal is depressed, the pressure initially increases slowly and then increases more quickly toward the travel limits of the pedal.

The system 20 receives the desired braking parameters L, R (as inputs from the pedals 21, 22) and is programmed by computer software to generate output braking parameters L ', R', the output braking parameters L ', R' being output to the brakes 13, 14 (as shown in FIG. 2) so that the

brakes

13, 14 apply the specified output braking parameters to their respective wheels the system 20 is programmed to generate these output braking parameters L ', R' using the logic shown in FIGS. 3 and 4.

First, the system 20 determines whether the aircraft is in a de-rotation phase by using the logic shown in FIG. 3, the de-rotation phase is the time when the

M L G components

11, 12 are on the ground and the N L G10 is not on the ground in flight immediately after landing.

The logic of FIG. 3 determines that the aircraft is in this de-rotation phase when: a) the aircraft speed is greater than the taxi speed (as determined at logic block 30); b) the nose gear is not on the ground or the aircraft pitch angle is greater than the natural pitch angle plus the deviation due to runway slope (as determined by AND logic block 31); c) the aircraft has previously taken off or the landing gear has been extended or retracted (as determined by or logic block 32); and d) the aircraft is not accelerating or experiencing high engine thrust (as determined by OR logic block 33). This last logic block 33 ensures that the control system 20 is able to distinguish between a phase of unwinding during landing and a similar phase of rotation during takeoff.

When the system 20 determines that the aircraft is in the de-spinning phase by using the logic of FIG. 3, then the system 20 converts the desired braking parameters L, R into output braking parameters L ', R' using the logic of FIG. 4 the upper half of FIG. 4 shows the logic for determining the left braking parameter L 'and the lower half of FIG. 4 shows the logic for determining the right braking parameter R'.

The logic of fig. 4 has a number of logic states (labeled as logic states a through F in table 1 below) that are designed to apply differential braking during unwinding without causing damage to the aircraft.

Table 1

The system 20 determines at the MIN logic blocks 40, 41 whether the sum of the left and right braking parameters (L + R) exceeds a threshold (T1), each

MIN logic block

40, 41 outputs the lowest of its two inputs, threshold T1 is set to a level above which there may be a risk of fatigue damage to N L G10 and other components at the front of the aircraft due to the high rate of unwinding when N L G10 lands.

If the sum (L + R) is greater than T1, system 20 determines a differential braking parameter (Δ L-R or R-L) that is the difference between the demand on the left brake and the demand on the right brake system 20 enters logical state B and sets L 'and R' equal amounts above and below T1/2, maintaining the differential braking parameter such that L '-R' L-R (again, R '-L' -R-L).

In logic state B, half of the differential demand Δ for L > R (i.e., for a left turn) is added to L ' and the other half is removed from R ', logic state B continues until it can no longer be removed from R ' (i.e., R ' ═ 0), at which time the system enters logic state C, and all additional demands are added to L '.

Similarly, for differential requests Δ of R > L (i.e., for right turns), half is added to R 'and the other half is removed from L' logical state B continues until it can no longer be removed from L '(i.e., L' is 0), at which point the system enters logical state D and all additional requests are added to R 'logical state D continues until a maximum threshold T2 is reached, at which point the system enters logical state F, defining R' as T2.

Thus, when the system is in logic state B, the left wheel is braked using a reduced left braking parameter L 'which is less than the desired left braking parameter L, and similarly, the right wheel is braked using a reduced right braking parameter R' which is less than the desired right braking parameter R reducing the braking parameters by the same amount is to maintain the differential braking parameter (Δ L-R or R-L) such that L '-R' L-R (or likewise R '-L' R-L.) and the sum of the reduced braking parameters (L '+ R') is set by the logic to be equal to the threshold T1.

Logic state B continues until differential braking parameter Δ exceeds T1. At this point, as long as the differential braking parameter Δ is less than T2, the system enters logic state C or D, operating a first of the brakes with the differential braking parameter Δ, and applying no braking torque to the other brake.

When the differential braking parameter Δ exceeds T2, then the system 20 enters logic states E or F, defining a first of the brakes as a threshold braking parameter T2, while maintaining the other brake at zero braking torque.

Table 2 below gives examples of the positions of the left and right pedals and their associated braking parameters and logic states based on 75% of the lower threshold value T1 and 100% of the upper threshold value T2. In this example, T2 is set quite high, and thus, the controller does not enter logic states E or F.

Table 2

Although the invention has been described above with reference to one or more preferred embodiments, it should be understood that various changes or modifications may be made without departing from the scope of the invention as defined in the appended claims.

For example, the system 20 described above receives the desired braking parameters L, R from the two pedals 21, 22 (as direct inputs), but in alternative embodiments of the invention, the pedals 21, 22 may be replaced with other user input devices in one embodiment of the invention, the pilot may input the total hydraulic pressure (equal to L + R in the above embodiment) with a first user input device and the differential braking parameter Δ (positive for left turns and negative for right turns) with a second user input device.

In the above embodiment, the control logic of fig. 4 is only used if the aircraft is in the de-spinning phase as determined by the logic of fig. 3. In an alternative embodiment of the invention, similar control logic can be used to define the load on other structural members in other critical phases (e.g., during low-speed coasting) by using different values of T1 and T2.

Claims

1. A method of braking respective left and right landing gear wheels of an aircraft on left and right sides includes receiving desired left braking parameters L for a left wheel, receiving desired right braking parameters R for a right wheel, braking the left wheel with a reduced left braking parameter L 'that is less than the desired left braking parameter L, and braking the right wheel with a reduced right braking parameter R' that is less than the desired right braking parameter R, wherein L '-R' L-R.

2. The method of claim 1, further comprising determining whether a sum L + R of the desired left braking parameter and the desired right braking parameter exceeds a threshold, braking the left wheel and the right wheel with the desired left braking parameter L and the desired right braking parameter R, respectively, in response to a determination that the sum L + R does not exceed the threshold, and braking the left wheel and the right wheel with the reduced left braking parameter L 'and the reduced right braking parameter R', respectively, in response to a determination that the sum L + R exceeds the threshold.

3. The method of claim 2, wherein the sum L '+ R' of the reduced braking parameters is substantially equal to the threshold value.

4. The method of any preceding claim, further comprising: determining a differential braking parameter indicative of a difference between the desired braking parameters; judging whether the differential braking parameter exceeds a threshold braking parameter; braking a first one of the wheels with the differential braking parameter in response to a determination that the differential braking parameter does not exceed the threshold braking parameter; and braking the first one of the wheels with the threshold braking parameter in response to a determination that the differential braking parameter exceeds the threshold braking parameter.

5. A method of braking first and second landing gear wheels, respectively, of an aircraft on first and second sides, the method comprising: receiving a first desired braking parameter for the first wheel; receiving a second desired braking parameter for a second wheel, wherein the second desired braking parameter is less than the first desired braking parameter; determining a differential braking parameter indicative of a difference between the desired braking parameters; judging whether the differential braking parameter exceeds a threshold braking parameter; braking the first wheel with the differential braking parameter in response to a determination that the differential braking parameter does not exceed the threshold braking parameter; and braking the first wheel with the threshold braking parameter in response to a determination that the differential braking parameter exceeds the threshold braking parameter.

6. The method of claim 5, wherein no braking torque is applied to the second wheel when the first wheel is braked with the differential braking parameter, and no braking torque is applied to the second wheel when the first wheel is braked with the threshold braking parameter.

7. A method according to any preceding claim wherein the aircraft is in a de-wind phase in which the landing gear wheels after landing are on the ground and the nose gear wheels of the aircraft are not on the ground.

8. The method of any preceding claim, further comprising: determining whether the aircraft is in an untwisting phase with the landing gear wheels on the ground and the nose gear of the aircraft not on the ground after landing; and performing the method in response to a determination that the aircraft is in the de-rotation phase.

9. A braking control system programmed to control left and right brakes of an aircraft by receiving desired left braking parameters L for the left brakes, receiving desired right braking parameters R for the right brakes, determining reduced left braking parameters L ', wherein the reduced left braking parameters L' are less than the desired left braking parameters L, determining reduced right braking parameters R ', wherein the reduced right braking parameters R' are less than the desired right braking parameters R, wherein L '-R' L-R, and outputting the reduced braking parameters to the left and right brakes.

10. A brake control system programmed to control first and second brakes of an aircraft by: receiving a first desired braking parameter for the first brake; receiving a second desired braking parameter for the second brake, wherein the second desired braking parameter is less than the first desired braking parameter; determining a differential braking parameter indicative of a difference between the desired braking parameters; judging whether the differential braking parameter exceeds a threshold braking parameter; outputting the differential braking parameter to the first brake in response to a determination that the differential braking parameter does not exceed the threshold braking parameter; and outputting the threshold braking parameter to the first brake in response to a determination that the differential braking parameter exceeds the threshold braking parameter.